The biggest baby boom since 1972 has helped the UK population grow at the fastest rate of any European country over the last 12 months, according to new figures.
Data from the Office for National Statistics show there were 813,200 births in the year to 30 June 2013 , compared with only 558,800 deaths.
The boost, combined with net migration of 156,600, added a total of 419,900 to the British population.
It means that Britain now has the third largest population in Europe, behind Germany and France.
Britain will become one of the world's most ethnically diverse countries in less than 40 years, an academic study has found.
The proportion of minority groups living in Britain will rise from 10% in 2006 to 40% by 2050, the Migration Observatory at the University of Oxford said.
The Observatory's Professor David Coleman said if current trends continue, the so-called majority-ethnic group in the UK - white British - will become a minority before 2070.
Prof Coleman said this assumption does not factor in the impact of current or future government attempts to reduce net migration.
"Migration has become the primary driver of demographic change in most high-income countries and may remain so.
"On current trends European populations will become more ethnically diverse, with the possibility that today's majority ethnic groups will no longer comprise a numerical majority in some countries."